1. Technical Field
The present invention relates to a device that is configured to circulate a cooling medium for an engine (hereinafter simply referred to as the “circulation device”).
2. Background Art
Conventional circulation devices having various configurations are known. For example, the configurations disclosed by Japanese Patents JP-A No. 140701/2001, JP-A No. 147292/2002, and JP-A No. 227646/2002 cool an EGR gas by circulating cooling water, which is introduced from a circulation path for engine cooling water, into an EGR cooler and exchanging heat between the cooling water and EGR gas. Here, an EGR (exhaust gas recirculation) technology is used to purify an exhaust gas of a diesel engine or the like. That is, in the EGR technology, part of the exhaust gas is recirculated to intake air to reduce the amount of NOx in the exhaust gas. This reduces the combustion temperature and inhibits the generation of NOx.